We have identified a new class of voltage-activated calcium channels with low thresholds and slow inactivation that are stimulated by protein kinase C in immortalized LHRH neurons. These channels are similar in amplitude to other voltage-activated calcium channels, but they are insensitive to block by conus toxins. We have also shown that large- conductance, calcium- and voltage-activated potassium channels in immortalized lactotrophs are inhibited by protein kinase C, which represents the first molecular mechanism linking phospholipase C activation to sustained increases in electrical excitability. We have extended our studies of potassium channel modulation by protein phosphatases to single channels in cell-free patches of membrane, and initiated experiments to investigate the role of hormonally activated protein phosphatases, elucidated by earlier studies from this laboratory, in neuronal degeneration associated with AIDS and Alzheimer's disease.